380 Dr. C. R. Alder Wright. [Jan. 28, 



It is noteworthy that the proportion between chloroform and water 

 thus deduced for the "limiting point " is close to that required for the 

 molecular ratio 2CHC1 3 , 5H 2 0. 



Calculated. 



2CHC1 3 239-0 = 72-64. 4216 = 



5H 2 O 90-0 = 27-36 16'21 = 



329-0 100-00 58-37 100-00 



But whether this' is merely an accidental coincidence, or is really due 

 to a tendency to form a definite hydrate of chloroform in presence of 

 acetic acid, cannot be decided by these experiments alone. The 

 results with alloys subsequently described rather suggest that it is 

 only a coincidence. 



Alloys of Lead, Tin, and Zinc. 



In Parts I and II seven different series of observations are recorded, 

 made with mixtures of lead, tin, and zinc, at temperatures varying 

 from about 565 C. up to near 800, and containing lead and zinc in 

 ' ratios varying from 2 : 1 to 1 : 2. On plotting these different series 

 on the triangular system, it is evident that the critical curves deduced 

 from those experiments where the temperature did not exceed 

 689 750 are substantially identical, whereas that derived from 

 experiments at a higher temperature, 750 850 averaging near 800, 

 lies perceptibly inside the others. Again, but little discordance 

 between the general directions and degrees of slope of the tie-lines 

 is noticed in any of the series at temperatures not above 750 where 

 the ratio of lead to zinc was 1:1 or 1 : 2 ; with the series where this 

 ratio was 2:1, however, the upper ties do not closely coincide 

 with those derived from the other series, but (as pointed out 

 by Sir G. G. Stokes, Part IV) are inclined to them at angles not 

 far from 5, thus indicating the existence of some cause constantly at 

 work interfering with separation into truly conjugate alloys ; obviously 

 this cause is the large preponderance of heavier alloy formed over 

 lighter alloy, which, as above stated, produces a marked effect on the 

 result by preventing thorough intermixture by stirring. 



On plotting out in these seven cases the values of {A A' (B B')} 2 

 as abscissas, and of A + A' andB + B'as ordinates (Stokes' 2nd method, 

 supra}, similar differences are observed. All the experiments at 

 565 750 concord fairly well when the series where the ratio of 

 lead to zinc was 1:1 or 1:2 are taken into account ; whereas the 

 series where the ratio was 2 : 1 exhibit a much wider departure. 

 The experiments at 750 850, and the concordant ones at 565 750 



